This article gives an overview of the supportive actions to be provided by the controller to a pilot when he/she is experiencing loss of positional orientation for a flight conducted under VFR and provides advice to controllers for handling such occurrences. This advice is derived from best practices and is not intended to supersede or replace local procedures.
Visual navigation conducted under VFR requires a continuous and conscious effort by the pilot to keep visual contact with the ground, maintain awareness of heading, speed and time, and to maintain constant awareness of terrain. The risks of loss of orientation and also somatogravic and somatogyral illusions are particularly high for flights conducted over featureless terrains even in perfect visual meteorological conditions (VMC).
Loss of Orientation by a VFR Flight – Effects on the Pilot
If a pilot becomes unaware of their exact position, common outcomes are airspace infringement, loss of separation and controlled flight into terrain (CFIT). In mountainous terrain, or in deteriorating weather conditions, the pilot may get into a situation where they do not have the aircraft performance or skills to avoid impact with terrain.
If, because of stress and/or loss of visual cues, the pilot becomes spatially disorientated, a condition which occurs when a pilot is unable to correctly interpret aircraft attitude, altitude or airspeed, then the outcome may be loss of control and CFIT.
What to expect as a controller:
- High level of stress in the cockpit – particularly for pilots who are less experienced with instrument flying techniques;
- Non-standard phraseology – the pilot might revert to non-standard phraseology when explaining the current situation, last known location or even might be reluctant to admit that visual orientation is lost.
- Random combination of manoeuvres – the pilot might start manoeuvring in order to gain visual contact with terrain regardless of unsafe proximity to terrain, to adjacent TMAs, danger areas and reserved airspace areas.
Suggested Controller's Actions
- Best practice, as embedded in the ASSIST principle, could be followed: (A - Acknowledge; S - Separate, S - Silence; I - Inform, S - Support, T - Time)
The loss of orientation might not be immediately obvious. Clarify with the pilot the actual status, especially when there is a doubtful, vague or non-standard RTF used to inform the loss of orientation.
- Advise the aircraft to climb to the minimum safe altitude while maintaining the flight in VMC. Prevention of CFIT has a priority but the ATCO shall avoid giving advice/clearances that will take the VFR flight into IMC for which the pilot may not be licensed. As a rule of thumb, ask the pilot if able to climb at the safe altitude and maintain the flight into VMC.
- If it is reported that visual contact with terrain is lost and it cannot be re-established without descending and that there is a risk of collision with terrain, instruct the aircraft crew to climb as necessary, underline the need for urgent action (climb due low altitude/due terrain etc.).
- Consult the minimum sector altitude chart and provide information to the pilot about the minimum safe altitudes. Exercise extra caution if the flight is conducted above mountainous terrain and there is a risk of severe turbulence;
- Clear all other aircraft in the vicinity of the aircraft in the abnormal situation, providing space for manoeuvres;
- Instruct the pilot to squawk 7700;
- Consider transferring other aircraft to a different frequency or imposing radio silence. Changing the frequency of an aircraft in an abnormal situation is more likely to result in a communication loss due to the stress experienced by the pilot.
- Inform the pilot as necessary about the distance to the nearest suitable aerodrome(s) and landing conditions;
- Provide time for the crew to decide on what course of action will be the safest, give time to assess all viable options such as fuel endurance, possibility to return back to the departure aerodrome or to deviate to the most suitable one;
- Provide navigational assistance to the crew as necessary by informing of magnetic track and distance to the aerodrome or specific geographical location;
- Assist the crew to identify a certain runway as necessary – provide runway magnetic orientation and/or coordinate increase of the runway lights intensity to help the visual acquisition;
- In case visual acquisition of the runway is not achieved and it is apparent that the pilot will continue the approach in IFR and/or marginal VMC:
- Inform the airport emergency services and all concerned parties according to local procedures;
- Ask if dangerous goods are on board;
- Ask for number of Persons On Board (POB);
- Clear RWY according to local instructions;
- Keep safety strip clear.
In general, to avoid the loss of visual terrain awareness, as a controller be proactive in the provision of assertive safety alert instructions, including the provision of the relevant minimum sector altitude to the affected aircraft. Provide prompt position information to an aircraft that has deviated from a cleared route, or whose observed position differs from the one being reported. Be aware that the flight crew can often be reluctant to declare a loss of orientation emergency.
- Personal Awareness - ATCOs should always be monitoring the course and altitude of traffic in his/her sector. Being constantly aware of any ongoing deviations should provide precious time for vectoring of nearby traffic.
- Adequate Reaction - Some of the possible actions: transfer all other aircraft to another frequency (possibly message all stations to increase awareness); leave the emergency traffic on the current frequency; increase the volume of the receiver; use common sense; have a colleague (a second pair of ears) to also listen to all transmissions from the aircraft.
- Technological Limitations - Try to keep the aircraft within radar cover. Keep in mind the features of the existing radar system.
- Organisational Awareness - Training of ATCOs for efficient handling of emergency situations should be an objective at administrative level. Periodic training and drills are likely to improve intra-organisational coordination.
A&I Events on SKYbrary involving loss of positional orientation
- SF34, vicinity Newcastle New South Wales Australia, 2012 - On 8 November 2012, the crew of a Saab 340B (VH-TRX) being operated by Regional Express on a scheduled passenger flight from Sydney to Newcastle lost positional awareness in day VMC after requesting and being granted visual positioning to the landing runway at destination. ATC observed that the aircraft was descending away from the expected approach and alerted and then assisted the crew to position to the approach for which they had been cleared.